JP2000006166A - Molding machine for thermosetting resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold apparatus for hardening a large-sized molding resin product while maintaining a size and a resin surface accuracy after molding and for relatively simply realizing a structure therefor. SOLUTION: An air-cooled jacket 5 is formed in a mold so as to surround a casting port 4. After a thermosetting resin is cast from the port 4 in the mold, a compressed air distributing unit 6 is detachably mounted at the port 4. After a compressed air from a high pressure air source is first supplied to the port 4 via the unit 6, the unit 6 is switched to heat the mold while continuously supplying it into the jacket 5, thereby hardening the resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding machine using a thermosetting resin such as an epoxy resin.

[0002]

2. Description of the Related Art Conventionally, in a molding machine using a thermosetting resin such as an epoxy resin, various measures have been taken in order to prevent the occurrence of sink marks on a molded product. The present applicant has already proposed as a utility model registration No. 2527303 a molding machine that injects compressed air into the injection port of a mold and heat-cures while maintaining the pressure of the injected resin to prevent the occurrence of sink marks. are doing. That is, when the molding resin product covered with an insulating material such as an epoxy resin changes from a liquid state to a solid state in the curing process, the volume is reduced due to the reaction shrinkage of the resin. The curing reaction also causes a reduction in volume due to heat shrinkage of the resin corresponding to the heating temperature. If the heating temperature in the vicinity of the casting mouth is relatively higher than that of the other parts and the curing reaction precedes, the replenishment of the resin from the casting mouth does not function effectively, and a so-called “sink” is locally formed on the resin surface. The target dent is generated.

[0003] The sink marks may cause defects in the use of the molded article depending on the location of the sink marks. For example, FIGS. 6 and 7
As shown in (1), when connecting GIS (bus of gas insulated switchgear, not shown) of power receiving equipment and VCT (transformer for current meter, not shown), the tank body 2 of both units is connected.
In the case where the spacer 21 attached between the flange portions 27 and 28 of each of the members 5 and 26 is manufactured by molding an epoxy resin, the spacers 21 serving as joint surfaces thereof are formed in the grooves 24 where the sealing members 23 are mounted. Occurs, the airtightness between the two units is not maintained, and the function as the spacer 21 cannot be performed.

Therefore, as a countermeasure against “sinking” of the mold portion, as described in Japanese Utility Model Registration No. 2527808 by the present applicant, a casting resin is previously filled with a supply resin corresponding to a shrinkage amount, and gold is poured. After sending compressed air to the mold casting opening, the casting opening is air-tightly closed, and the primary curing is performed while maintaining the pressurized state, thereby preventing the occurrence of sink marks.
In addition, reference numeral 29 in FIG. 6 denotes an insert which becomes a conductor of the spacer 21.

[0005]

However, in the above-described apparatus, in practice, the mold body is put together with the resin and the circuit conductor, and the entire body is uniformly heated so that the temperature rise of each part is made uniform and hardened. Is extremely difficult. In addition, depending on conditions such as the heating temperature and the composition ratio of the base and the curing agent during the curing process, the temperature of the resin in the vicinity of the casting opening or the resin filled in the casting opening becomes higher than that of other main parts, and the gel is formed first. (Solidification), and the replenishment resin may not be replenished, causing “sink”.

[0006] As another device, there is a device in which a mold is provided with a temperature gradient and is sequentially cured from a high temperature side to obtain a molded resin product having good dimensions and resin surface accuracy. A heat source and a temperature sensor are embedded in the mold body, and a strong mold structure and assembly drive are required.
The arrangement and wiring of the embedded device become large-scale, making the device expensive. Therefore, the present invention provides a mold apparatus that can be cured while maintaining the dimensions and resin surface accuracy after molding of a large-sized molded resin product, and the structure for that can be realized relatively easily. Was an issue.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a method in which a thermosetting resin is injected into a mold through a casting port, and then the casting port is compressed by compressed air. In a thermosetting resin molding machine that heats the mold under pressure and cures the resin, an air-cooling jacket is formed in the mold so as to surround the casting port, and continuous inside this jacket. The method is characterized in that the mold is heated while the compressed air is supplied to cure the resin.

According to a second aspect of the present invention, in the first aspect of the present invention, a three-way valve is removably attached to a casting opening and a jacket of the mold after the resin is injected, and compressed air is cast through the three-way valve. After supplying the compressed air to the mouth, the three-way valve is switched to supply compressed air to the jacket.

According to a third aspect of the present invention, in the second aspect of the present invention, an air supply port to the jacket is formed near the casting port on the mold end surface where the casting port is formed. .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment in which the present invention is applied to a molding machine in which a spacer which is a part of a circuit conductor of a large electric device is molded by using an epoxy resin will be described. FIG. 1 is a view showing a structure of a main part of a molding machine, and one mold is removed to show the inside of the mold. FIG. 2 shows FIG.
3 is a sectional view taken along line AA of FIG. In these figures, a part is emphasized more than an actual dimensional ratio for explanation. In the figure, 1A, 1B
Denotes a mold having a two-part structure, and 2 denotes an insert serving as an electric conductor of the spacer. A casting port (sprue) 4 is formed in the upper part of the molds 1A and 1B in the vertical direction, and a jacket 5 for air cooling is formed in the peripheral body of the molds 1A and 1B.

The upper end of the jacket 5 is opened on the upper surfaces of the dies 1A and 1B, like the upper end of the casting port 4. In the state shown in the figure, the insert 2 is inserted into the dies 1A and 1B, the dies 1A and 1B are joined, and after the heat treatment, the epoxy resin 3 is injected from the injection port 4, and the injection port 4 is formed. Unfilled space is left at the top of the. When a predetermined amount of the epoxy resin 3 is injected, a compressed air distribution device 6 as a three-way valve is attached to the upper surfaces of the molds 1A and 1B so as to cover the casting port 4 and the opening of the jacket 5. . At this time, the compressed air distribution device 6 is hermetically attached to the dies 1A and 1B via bolts or other fastening means via a seal member (not shown).

As shown in the longitudinal sectional views of FIGS. 4 and 5, the compressed air distribution device 6 has an input passage 11 formed at an upper portion, a pressurizing passage 12 and a cooling passage 13 formed at a lower portion, and between them. A diversion control valve 7 that reciprocates left and right is mounted. A condenser hose 9 from a compressor (not shown), which is a high-pressure air source, is connected to the input passage 11. With the compressed air distribution device 6 installed, the lower end of the pressurizing passage 12 is located at the upper end of the casting port 4, and the lower end of the cooling passage 13 is located at the opening of the jacket 5. The flow dividing control valve 7 of the compressed air flow dividing device 6 is provided with an airtight mechanism with other passages, a detent, a locking mechanism, and the like, although not particularly specified.

[0013] The compressed air distribution device 6 is a mold 1A, 1B
In the first state, the flow control valve 7 is moved to the left to switch the switching passage 14 to the pressurizing passage 1 as shown in FIG.
2, the compressed air from the input passage 11 is supplied to the casting port 4 via the pressurizing passage 12. The compressed air is injected into an unfilled space above the casting port 4 and rises instantaneously to the supply pressure. Next, by moving the flow dividing control valve 7 of the compressed air distribution device 6 to the right, the switching passage 14 matches the cooling passage 13, and the compressed air is supplied to the cooling passage 13.

At this time, the pressurizing passage 12 and the casting port 4
The upper unfilled space is sealed, so that a high pressure state is maintained. The compressed air from the cooling passage 13 is sent to the jacket 5 and adiabatically expanded, thereby lowering the temperature of the compressed air itself and cooling the molds 1A and 1B, that is, the casting port 4.
Next, the compressed air is discharged to the exhaust hose 8 via the exhaust passage formed on the mold 1B side. With the casting port 4 thus cooled, the entire mold is placed inside a heating and curing furnace (not shown) and heating is started.

As a result, the mold apparatus arranged in the heat-curing furnace, by the partial cooling of the compressed air, raises the heating temperature of the replenishing resin 3a in the casting port 4 to the main part of the resin 3 And the curing reaction time is delayed. On the other hand, the main part of the resin 3 starts to be cured prior to heating. Next, the replenishment resin 3a in the casting port 4, which has not yet been cured, moves to the main body side and the reduced amount is replenished by an amount corresponding to the reduced volume due to the shrinkage of the resin 3 in the main part. Thereby, the resin 3 of the main part is cured along the shape of the inner surface of the mold and while satisfying the required surface accuracy.

Further, in this embodiment, since the hose is used for supplying and discharging the compressed air, it has flexibility in routing and moving the arrangement. Further, in the heating / hardening furnace, it is easy to draw in the hose from a predetermined hose insertion port or to route the hose appropriately, and it is not necessary to newly remodel the heating / hardening furnace when expanding its space or adding additional equipment. Furthermore,
The use of a branch hose can easily cope with the case where a plurality of mold devices are to be arranged in a heating and curing furnace for mass production. As described above, according to the present invention, it is possible to manufacture even a large-sized molded resin product requiring strict dimensions and resin surface accuracy after molding without using a large-scale and expensive mold apparatus.

In the above-described embodiment, the compressed air distribution device 6 is installed to supply the compressed air to the casting port 4 first, and then to the jacket 5. It is also possible to adopt a configuration in which compressed air is simultaneously supplied to the casting port 4 and the jacket 5 by different systems without being provided. Further, in the embodiment, the upper end of the jacket 5 is opened to the upper surface of the mold and is covered by the main body of the compressed air distribution device 6, but the air supply port may be separately formed as a structure that does not open the upper surface of the mold. It is possible.

[0018]

As described above, according to the present invention, since the mold is heated while cooling the resin in the casting port by forming a jacket at the casting port portion, the resin in the casting port portion can be heated. The curing is delayed by that much, and the resin shrunk by the curing of the molded article main body is surely replenished from the casting opening portion, thereby eliminating the occurrence of sink marks.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a main part of an embodiment of the present invention.

FIG. 2 is a right side view of FIG.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a longitudinal sectional view showing an operation state of the compressed air distribution device of FIG.

FIG. 5 is a longitudinal sectional view showing an operation state of the compressed air distribution device of FIG.

FIG. 6 is a diagram showing a conventional example.

FIG. 7 is an enlarged view of a portion B in FIG. 6;

[Explanation of symbols]

 Reference Signs List 1A, 1B Mold 2 Insert 3 Epoxy resin 4 Casting port 5 Jacket 6 Compressed air distribution device 7 Distribution control valve 8 Exhaust hose 9 Condenser hose 11 Input passage 12 Pressurizing passage 13 Cooling passage 14 Switching passage

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29K 105: 24

Claims (3)

[Claims] 1. A thermosetting resin for injecting a thermosetting resin into a mold through a casting port and then heating the mold in a state where the casting port is pressurized by compressed air to cure the resin. In the molding machine, an air cooling jacket is formed in the mold so as to surround the casting port, and the resin is cured by heating the mold while continuously supplying compressed air into the jacket. Characteristic molding machine for thermosetting resin. 2. A molding machine for a thermosetting resin according to claim 1, wherein a three-way valve is detachably attached to a casting port and a jacket of the mold after the resin is injected, and compressed air is injected through the three-way valve. A thermosetting resin molding machine, characterized in that a three-way valve is switched to supply compressed air to a jacket after being supplied to a mold opening. 3. The molding machine for a thermosetting resin according to claim 2, wherein an air supply port to the jacket is formed near the casting port on the mold end face where the casting port is formed. Thermosetting resin molding machine.